Figure 4.

Reduced Cortical Response in CIP Patient to Capsaicin Challenge

(A) The comparison of the group mean verbal pain intensity ratings collected during the “thermal + capsaicin” condition between the CIP and healthy controls (HC) (Mann-Whitney U test, ^∗p < 0.001). For HC, the error bars represent the SEM for the group (n = 12). Here, each healthy control participant was scanned once. During this scan, a single trial testing the effects of each experimental condition once was observed for that subject. Multiple-repeat trials were not collected on the HC cohort. For the single CIP patient, the error bars represent the SEM across repeated trials for that patient. The CIP patient was scanned twice. In each CIP scan session, three repeat trials were collected for each experimental condition. A total of six trials were included in the analysis of the CIP patient.

(B) A schematic of the experimental paradigm used to image CIP patient. The schematic represents a single scan session. The four experimental conditions: Rest, Thermal, Capsaicin, and Thermal + Capsaicin (“Therm.+Cap.”) are displayed as colored boxes. Three 5-min scan runs (i.e., r1, r2, r3) were collected for each condition. The 25-min capsaicin onset phase is displayed as an inverted “z.” No FMRI data were collected here.

(C) The mean change in CBF elicited by the contrast of “thermal + capsaicin versus rest” for CIP (top row) and healthy controls (HC) (bottom row) (mixed effects; z > 3.1, p < 0.05). Regions showing an increase in CBF during “thermal + capsaicin > rest” are displayed in red.

(D) Comparison of the group mean neurological pain signature (NPS) response values observed from the “thermal + capsaicin > rest” contrast images at the subject level (Mann-Whitney U test, ^∗p < 0.001). Data from repeated trials were processed as in (A).